The use of endoscopic procedures in surgery has become widely accepted. The term endoscopic as used herein is defined to include laparoscopic and arthroscopic. Numerous endoscopic instruments have been developed which allow the surgeon to perform complex surgical procedures with minimal incisions into the skin and tissue surrounding a particular body cavity. In order to introduce the endoscopic instrumentation into the body cavity, it is first necessary to puncture and cannulate the body cavity by using a trocar. Trocars are widely known in the art and typically consist of an obturator and a trocar cannula. Trocars may have a protective housing around the obturator which covers the sharp piercing tip of the obturator prior to and after insertion, and also after removal of the obturator and trocar cannula.
One type of trocar is typically inserted by pressing the distal end of the trocar assembly against the outer skin of the patient with sufficient force to cause the piercing end of the obturator to pierce through the skin, underlying fat, muscle and fascia into the body cavity. Once the surgeon has properly positioned the trocar within the body cavity, the obturator and protective housing are removed, and the trocar cannula is then available as a pathway, e.g., for insertion of endoscopic instrumentation.
Conventionally, trocar cannulas typically consist of a distal cannula tube and a proximal cannula handle. The cannula tube is inserted into a patient along with the obturator, while the proximal handle of the trocar cannula typically remains outside of the patient. Trocar cannula handles typically contain a spring-loaded flapper-type valve which seals the proximal opening of the trocar cannula, thereby allowing the patient's body cavity to remain insufflated with a gas by preventing the gas from escaping through the trocar cannula. The trocar cannula handle typically has an exterior control lever to manually control the position of the flapper valve and to indicate the position of the flapper valve.
As technical know-how is developed, there have been improvements made in the design and construction of trocar cannulas, and surgical techniques involving the use of trocar cannulas in endoscopic procedures have likewise progressed; however, there are deficiencies associated with the use of conventional trocars. In particular, conventional trocar cannulas are made of opaque materials. During an endoscopic surgical procedure, the surgeon has a relatively good view of the targeted surgical site through the use of an endoscope. However, there is one part of an endoscopic surgical procedure which cannot be viewed. Specifically, the insertion of surgical instruments, needles, clips, etc. through the trocar cannula cannot be observed, since as mentioned previously, conventional trocar cannulas are opaque. Similarly, the withdrawal of the instruments, needles, clips, etc., through the trocar cannula cannot be observed.
In addition, it is typical in many endoscopic procedures to remove a tissue specimen from a body cavity through a trocar. Once again, the surgeon loses visual contact with the tissue from the time it enters the distal end of the trocar cannula tube in the body cavity until it exits the proximal end of the trocar cannula handle.
Also, it is not uncommon for a surgeon to lose a needle or a staple within a patient during surgery. This often necessitates a search within the patient for the missing object, prolonging the operative procedure and subjecting the patient to additional risk. During an endoscopic procedure, needles or staples may be accidently lodged in a trocar cannula tube or the trocar cannula handle. Since conventional trocar cannulas are opaque, the surgeon may not realize that the needle or staple has become lodged in the trocar cannula and may search the patient's body cavity in an attempt to retrieve the missing needle or staple. Such a search, although necessary, constitutes a needless risk to the patient.
Additionally, delicate surgical instruments may be damaged during insertion into or removal from a trocar cannula if appropriate care is not taken. It is possible for an instrument to be hung-up and possibly damaged in the trocar cannula handle as the surgeon attempts to maneuver the instrument around the flapper valve and through the trocar handle and into the proximal opening of the trocar cannula tube. Since the handles of conventional trocar cannulas are opaque, this must be done by feel. This deficiency is particularly evident when the surgeon attempts to insert a small diameter instrument through a relatively larger diameter trocar cannula.
Similarly, when attempting to remove tissue specimens through a trocar cannula from a body cavity, it is possible that the surgeon may cause the tissue specimens to be damaged, or the tissue specimens may be disengaged from extraction instruments and released within the trocar cannula, or lodged within the trocar cannula tube or handle, or even fall back into the body cavity. This is further exacerbated by the fact that the surgeon cannot observe the specimen from the time it enters the distal end of the trocar cannula tube until it is withdrawn from the proximal end of the trocar cannula handle.
There are yet additional deficiencies associated with the use of trocar cannulas relating to the flapper valve. Most endoscopic surgical procedures require that the patient's body cavity be insufflated to provide sufficient room to maneuver endoscopic instruments. This is typically done by pressurizing the patient's body cavity with a source of pressurized, sterile gas, e.g., carbon dioxide. This gas is prevented from escaping through trocar cannulas the by the previously mentioned flapper valves and also by gaskets, conventionally contained in trocar cannulas, which engage the outer surfaces of instruments inserted through the trocar cannulas, thereby providing gas-tight seals. However, a slight displacement of a flapper valve in a trocar cannula handle from a fully seated position may be sufficient to cause a gas leak which may result in a rapid volumetric loss of gas from the patient's body cavity. The exact position of the flapper valve in a conventional trocar cannula is not immediately ascertainable by the surgeon, making it more difficult to take immediate action to remedy a gas leak. Flapper valve position indicators are conventionally utilized on trocar cannulas, but the indicators show gross displacement. It is possible to have a slight flapper valve displacement sufficient to allow gas to escape even though the indicator shows that the valve is in a closed position. The displacement may be caused, unknown to the surgeon, by a piece of tissue, or a needle, or a staple being hung-up in the flapper valve assembly. Since the surgeon cannot see the cause of the problem, remediation is difficult and, once again, this introduces an additional, unnecessary risk to the patient. For example, the surgeon, when confronted with a gas leak through the trocar cannula, may be forced to remove the trocar cannula from the body cavity and insert a replacement, again introducing another element of risk to the patient.
Therefore, what is needed in this field are trocar cannulas which overcome the deficiencies associated with conventional trocars. What is also needed is a method of performing an endoscopic surgical procedure which overcomes the deficiencies associated with the use of conventional trocar cannulas.